The invention relates to an apparatus for successively making plastic bags.
There has been proposed an apparatus for successively making plastic bags each of which comprises a pair of panel portions, first and second side gusset portions and a bottom gusset portion, as disclosed in U.S. Patent Application Publication No. US-2001-0002938-A1. The pair of panel portions are superposed with each other to define aligned top edges, first and second side edges and bottom edges. The first side gusset portion is disposed between the first side edges to extend therealong. The second side gusset portion is disposed between the second side edges to extend therealong. Each of the side gusset portions is folded into halves along a centerline extending longitudinally thereof, to be superposed into two layers and interposed between the pair of panel portions. The first side edges are connected with each other by means of the first side gusset portion, the second side edges being connected with each other by means of the second side gusset portion.
On the other hand, the bottom gusset portion is disposed between the bottom edges to extend therealong. The bottom gusset portion is also folded into halves along a centerline extending longitudinally thereof, to be superposed into two layers and interposed between the pair of panel portions. The bottom edges are connected with each other by means of the bottom gusset portion. In addition, the bottom gusset portion has first and second ends at which first and second auxiliary gusset portions are formed. Each of the auxiliary gusset portions is folded from the bottom gusset portion along folded lines extending at an angle of about 45xc2x0 with respect to the centerline of bottom gusset portion. The first auxiliary gusset portion is further folded into halves along a centerline which is an extension of the centerline of bottom gusset portion, to be superposed into two layers one of which is interposed along with one of the layers of bottom gusset portion between one of the panel portions and one of the layers of first side gusset portion. The other layer of first auxiliary gusset portion is interposed along with the other layer of bottom gusset portion between the other panel portion and the other layer of first side gusset portion. The first side gusset portion is connected with the bottom gusset portion by means of the first auxiliary gusset portion. The second auxiliary gusset portion is further folded into halves along a centerline which is an extension of the centerline of bottom gusset portion, to be superposed into two layers one of which is interposed along with one of the layers of bottom gusset portion between one of the panel portions and one of the layers of second side gusset portion. The other layer of second auxiliary gusset portion is interposed along with the other layer of bottom gusset portion between the other panel portion and the other layer of second side gusset portion. The second side gusset portion is connected with the bottom gusset portion by means of the second auxiliary gusset portion.
Accordingly, the plastic bag is advantageous in that the first and second side gusset portions can be unfolded between the first and second side edges respectively to obtain a large capacity. The bottom gusset portion and the first and second auxiliary gusset portions can be unfolded between the bottom edges to constitute a rectangular bottom. The plastic bag can therefore stably stand on a table.
In order to make such the plastic bags in the apparatus, a main or panel material is fed longitudinally thereof and intermittently for a length. The panel material includes a pair of panel portions superposed with each other to define aligned first and second side edges. The panel material further includes a first side gusset portion disposed between and extending along the first side edges and a second side gusset portion disposed between and extending along the second side edges.
In addition, one of the panel portions is cut as well as the first and second side gusset portions widthwise of the panel material so that an opening can be formed in the panel material whenever the panel material is fed intermittently. An additional or bottom gusset material is then inserted between the pair of panel portions through the opening whenever the panel material is fed intermittently. Furthermore, the bottom gusset material is guided by guide means to be folded into a predetermined shape when being inserted between the pair of panel portions so that the bottom gusset portion and the first and second auxiliary gusset portion can be formed out of the bottom gusset material. The bottom gusset portion is folded into halves. The first and second auxiliary gusset portions are folded from the bottom gusset portion and folded into halves.
Furthermore, the apparatus includes folded tendency means for making the bottom gusset material having a tendency to be folded before being inserted between the pair of panel portions. For example, the folded tendency means comprises a heater for heating and pressurizing the bottom gusset material to make it having a tendency to be folded. The bottom gusset material is then guided by the guide means to be folded. Accordingly, the bottom gusset material can be conveniently folded into the predetermined shape and then inserted between the panel portions.
The panel material and the bottom gusset material are then fed intermittently by means of the other panel portion and heat sealed with each other by heat seal means. In addition, a cutter cuts the panel material to make the plastic bag.
However, the apparatus involves the folded tendency means to be high in cost. In addition, the bottom gusset material comprises a laminated plastic film including a sealant which is laminated on a base material. The sealant may therefore be damaged when making the bottom gusset material having the tendency to be folded, spoiling property of gas barrier and resulting in pin holes.
It is therefore an object of the invention to provide a new and improved apparatus for successively making plastic bags, to thereby overcome the above problems.
Other object of the invention is to provide the apparatus in which a panel material is fed longitudinally thereof and intermittently for a length. The panel material includes a pair of panel portions superposed with each other to define aligned first and second side edges. The panel material further includes a first side gusset portion disposed between and extending along the first side edges and a second side gusset portion disposed between and extending along the second side edges. One of the panel portions is cut as well as the first and second side gusset portions widthwise of the panel material so that an opening can be formed in the panel material whenever the panel material is fed intermittently. A bottom gusset material is then inserted between the pair of panel portions through the opening whenever the panel material is fed intermittently.
Other object of the invention is to provide the apparatus in which the bottom gusset material can be conveniently folded into a predetermined shape and then inserted between the panel portions, without making the bottom gusset material having a tendency to be folded.
According to the invention, the apparatus comprises a trapezoidal plate including a short edge having opposite ends from which opposite oblique edges extend divergently. The trapezoidal plate comprises a double walled structure in which clearance means is formed between walls.
The apparatus further comprises drive means by which the trapezoidal plate is moved in a direction of height of trapezoid so that the short edge can be engaged with the bottom gusset material.
In addition, the apparatus comprises a pair of folding plates arranged to be engaged with the bottom gusset material and then inserted into the clearance means at positions corresponding to the oblique edges in accordance with the movement of the trapezoidal plate so that the bottom gusset material can be inserted into the clearance means by the folding plates to be folded into halves along the short edge and folded into the clearance means along the oblique edges. The bottom gusset material is then inserted between the pair of panel portions.
In other embodiment, the apparatus comprises a triangular plate including an apex portion from which opposite oblique edges extend divergently. The triangular plate comprises a double walled structure in which clearance means is formed between walls.
The apparatus further comprises drive means by which the triangular plate is moved in a direction of height of triangle so that the apex portion can be engaged with the bottom gusset material.
In addition, the apparatus comprises a pair of folding plates arranged to be engaged with the bottom gusset material and then inserted into the clearance means at positions corresponding to the oblique edges in accordance with the movement of the triangular plate so that the bottom gusset material can be inserted into the clearance means by the folding plates to be folded into halves at the apex portion and folded into the clearance means along the oblique edges. The bottom gusset material is then inserted between the pair of panel portions.